In Situ Growth of Bi Nanoparticles on NaBiO₃, δ‑, and β‑Bi₂O₃ Surfaces: Electron Irradiation and Theoretical Insights

Herein, we present a combined experimental and theoretical study of the in situ growth of Bi nanoparticles on NaBiO₃, δ-, and β-Bi₂O₃ surfaces mediated by the electron beam of a high-resolution transmission electron microscope. Density functional theory and quantum theory of atoms in molecule calculations were used to gain a deeper insight into the experimental observations and to provide an atomistic basis for understanding the formation mechanism of Bi NPs on NaBiO₃, δ-, and β-Bi₂O₃ under electron beam irradiation. Analysis of the experimental data and electron density distributions suggests that the formation of Bi NPs can be related to the structural and electronic changes occurring within the octahedral [BiO₆] clusters, and to a lesser extent, [NaO₆] clusters, which serve as the constituent building blocks of NaBiO₃. Our findings indicate that as a function of the number of added electrons, the formation of β-Bi₂O₃ takes place first followed by the subsequent appearance of metallic Bi NPs generated in the crystal by electron beam irradiation.